syzbot

 sign-in | mailing list | source | docs
🐞 Open [445]
🐞 Fixed [20]
🐞 Invalid [123]
⬇ Missing Backports [17]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
💬 Send us feedback

INFO: rcu detected stall in sys_clone (2)

Status: upstream: reported on 2025/12/09 09:13
Reported-by: syzbot+7919861b650883ef99d9@syzkaller.appspotmail.com
First crash: 35d, last: 13d
▶ ▼ Similar bugs (17)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 INFO: rcu detected stall in sys_clone 1 C done 8 70d 154d 2/2 fixed on 2025/12/06 23:11
linux-5.15 INFO: rcu detected stall in sys_clone 1 1 769d 769d 0/3 auto-obsoleted due to no activity on 2024/03/15 18:08
linux-6.1 INFO: rcu detected stall in sys_clone 1 3 916d 988d 0/3 auto-obsoleted due to no activity on 2023/10/20 18:18
upstream INFO: rcu detected stall in sys_clone (2) mm 1 49 2142d 2259d 0/29 auto-closed as invalid on 2020/06/01 05:26
upstream INFO: rcu detected stall in sys_clone (4) kernel 1 1 1659d 1659d 0/29 auto-closed as invalid on 2021/09/27 17:49
upstream INFO: rcu detected stall in sys_clone (3) mm 1 2 1995d 2017d 0/29 auto-closed as invalid on 2020/10/26 22:48
upstream INFO: rcu detected stall in sys_clone (6) kasan mm 1 1 1330d 1330d 0/29 auto-closed as invalid on 2022/08/23 03:28
upstream INFO: rcu detected stall in sys_clone kernel 1 1 2315d 2315d 13/29 fixed on 2019/10/09 10:54
upstream INFO: rcu detected stall in sys_clone (8) mm 1 C error 368 4h16m 656d 0/29 upstream: reported C repro on 2024/03/29 00:16
linux-4.19 INFO: rcu detected stall in sys_clone 1 2 2213d 2232d 0/1 auto-closed as invalid on 2020/04/21 05:46
upstream INFO: rcu detected stall in sys_clone (5) kernfs 1 5 1464d 1563d 0/29 closed as invalid on 2022/02/08 10:00
upstream INFO: rcu detected stall in sys_clone (7) fs 1 1 1065d 1065d 0/29 auto-obsoleted due to no activity on 2023/05/14 17:18
linux-5.15 INFO: rcu detected stall in sys_clone (2) missing-backport origin:upstream 1 C done 72 9h57m 658d 0/3 upstream: reported C repro on 2024/03/27 00:16
linux-6.1 INFO: rcu detected stall in sys_clone (2) origin:upstream missing-backport 1 C error 40 14d 664d 0/3 upstream: reported C repro on 2024/03/20 15:17
android-5-10 BUG: soft lockup in sys_clone 1 1 554d 554d 0/2 auto-obsoleted due to no activity on 2024/10/06 12:58
android-5-10 BUG: soft lockup in sys_clone (2) 1 1 129d 129d 0/2 auto-obsoleted due to no activity on 2025/12/06 02:03
android-5-15 BUG: soft lockup in sys_clone origin:upstream 1 C error 18 490d 633d 0/2 auto-obsoleted due to no activity on 2024/12/19 12:14

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 ticks this GP) idle=9854/1/0x4000000000000000 softirq=31028/31028 fqs=0
rcu: 	(detected by 0, t=10502 jiffies, g=36077, q=283 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5767 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:lock_acquire+0x1f2/0x410 kernel/locking/lockdep.c:5758
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f5 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 66 43 c7 44 3c 09 00 00 43 c6 44 3c 0b 00
RSP: 0018:ffffc900001f0ae0 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 0000000000000000 RCX: f8b441858534c600
RDX: 0000000000000000 RSI: ffffffff8aaace60 RDI: ffffffff8afc6f80
RBP: ffffc900001f0be8 R08: dffffc0000000000 R09: 1ffffffff21b28a0
R10: dffffc0000000000 R11: fffffbfff21b28a1 R12: 1ffff9200003e168
R13: ffffffff970e56c0 R14: 0000000000000046 R15: dffffc0000000000
FS:  00005555915aa500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbdd9618f70 CR3: 0000000060aba000 CR4: 00000000003526e0
Call Trace:
 <IRQ>
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xa8/0xf0 kernel/locking/spinlock.c:162
 debug_object_activate+0x6c/0x4b0 lib/debugobjects.c:709
 debug_hrtimer_activate kernel/time/hrtimer.c:450 [inline]
 debug_activate kernel/time/hrtimer.c:505 [inline]
 enqueue_hrtimer+0x30/0x370 kernel/time/hrtimer.c:1108
 __run_hrtimer kernel/time/hrtimer.c:1767 [inline]
 __hrtimer_run_queues+0x637/0xc40 kernel/time/hrtimer.c:1814
 hrtimer_interrupt+0x3c9/0x9c0 kernel/time/hrtimer.c:1876
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline]
 __sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:rcu_rnp_online_cpus kernel/rcu/tree.c:4182 [inline]
RIP: 0010:rcu_rdp_cpu_online kernel/rcu/tree.c:4192 [inline]
RIP: 0010:rcu_lockdep_current_cpu_online+0xbf/0x120 kernel/rcu/tree.c:4233
Code: 18 48 89 d8 48 c1 e8 03 42 80 3c 30 00 74 08 48 89 df e8 54 16 6d 00 48 8b 1b 48 83 c3 70 48 89 d8 48 c1 e8 03 42 80 3c 30 00 <74> 08 48 89 df e8 37 16 6d 00 4c 85 3b 75 1a 48 c7 c7 80 5a d3 8c
RSP: 0018:ffffc900044ff488 EFLAGS: 00000246
RAX: 1ffffffff19a6a3e RBX: ffffffff8cd351f0 RCX: f8b441858534c600
RDX: 0000000000000000 RSI: ffffffff8afc6f60 RDI: ffff8880b8f3cf20
RBP: 0000000000000001 R08: dffffc0000000000 R09: 1ffffffff21b28a0
R10: dffffc0000000000 R11: fffffbfff21b28a1 R12: dffffc0000000000
R13: 00000000000001a0 R14: dffffc0000000000 R15: 0000000000000002
 rcu_read_lock_held_common kernel/rcu/update.c:112 [inline]
 rcu_read_lock_held+0x1e/0x40 kernel/rcu/update.c:348
 lookup_page_ext mm/page_ext.c:240 [inline]
 page_ext_get+0x193/0x2b0 mm/page_ext.c:509
 page_table_check_set+0x51/0x6f0 mm/page_table_check.c:114
 page_table_check_ptes_set include/linux/page_table_check.h:74 [inline]
 set_ptes include/linux/pgtable.h:238 [inline]
 copy_present_pte mm/memory.c:979 [inline]
 copy_pte_range mm/memory.c:1083 [inline]
 copy_pmd_range mm/memory.c:1168 [inline]
 copy_pud_range mm/memory.c:1205 [inline]
 copy_p4d_range mm/memory.c:1229 [inline]
 copy_page_range+0x248d/0x3600 mm/memory.c:1323
 dup_mmap kernel/fork.c:764 [inline]
 dup_mm kernel/fork.c:1692 [inline]
 copy_mm+0x11a8/0x1ca0 kernel/fork.c:1741
 copy_process+0x16d3/0x3d70 kernel/fork.c:2506
 kernel_clone+0x21b/0x840 kernel/fork.c:2914
 __do_sys_clone kernel/fork.c:3057 [inline]
 __se_sys_clone kernel/fork.c:3041 [inline]
 __x64_sys_clone+0x18c/0x1e0 kernel/fork.c:3041
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f84e4185e93
Code: 1f 84 00 00 00 00 00 64 48 8b 04 25 10 00 00 00 45 31 c0 31 d2 31 f6 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 89 c2 85 c0 75 2c 64 48 8b 04 25 10 00 00
RSP: 002b:00007fff07cc6808 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f84e4185e93
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001
R10: 00005555915aa7d0 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000036 R14: 0000000000044d53 R15: 00007fff07cc69a0
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g36077 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=19285
rcu: rcu_preempt kthread starved for 10502 jiffies! g36077 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:I stack:27432 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_timeout+0x160/0x280 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5767 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__lock_is_held kernel/locking/lockdep.c:5492 [inline]
RIP: 0010:lock_is_held_type+0xb1/0x190 kernel/locking/lockdep.c:5825
Code: 7e 4b 44 89 fd 49 89 df 49 81 c7 e0 0a 00 00 45 31 e4 49 83 fc 31 73 24 4c 89 ff 4c 89 f6 e8 26 02 00 00 85 c0 75 2a 49 ff c4 <48> 63 83 d8 0a 00 00 49 83 c7 28 49 39 c4 7c d8 eb 11 48 c7 c7 60
RSP: 0018:ffffc900001f0c28 EFLAGS: 00000002
RAX: 0000000000000000 RBX: ffff88802b678000 RCX: 0000000000000000
RDX: ffff88802b678000 RSI: ffff888026a4e300 RDI: ffff88802b678b58
RBP: 00000000ffffffff R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff5200003e17c R12: 0000000000000004
R13: 0000000000000046 R14: ffff888026a4e300 R15: ffff88802b678b58
FS:  00005555915aa500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbdd9618f70 CR3: 0000000060aba000 CR4: 00000000003526e0
Call Trace:
 <IRQ>
 lock_is_held include/linux/lockdep.h:288 [inline]
 advance_sched+0xe8/0xc80 net/sched/sch_taprio.c:941
 __run_hrtimer kernel/time/hrtimer.c:1750 [inline]
 __hrtimer_run_queues+0x51e/0xc40 kernel/time/hrtimer.c:1814
 hrtimer_interrupt+0x3c9/0x9c0 kernel/time/hrtimer.c:1876
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline]
 __sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:rcu_rnp_online_cpus kernel/rcu/tree.c:4182 [inline]
RIP: 0010:rcu_rdp_cpu_online kernel/rcu/tree.c:4192 [inline]
RIP: 0010:rcu_lockdep_current_cpu_online+0xbf/0x120 kernel/rcu/tree.c:4233
Code: 18 48 89 d8 48 c1 e8 03 42 80 3c 30 00 74 08 48 89 df e8 54 16 6d 00 48 8b 1b 48 83 c3 70 48 89 d8 48 c1 e8 03 42 80 3c 30 00 <74> 08 48 89 df e8 37 16 6d 00 4c 85 3b 75 1a 48 c7 c7 80 5a d3 8c
RSP: 0018:ffffc900044ff488 EFLAGS: 00000246
RAX: 1ffffffff19a6a3e RBX: ffffffff8cd351f0 RCX: f8b441858534c600
RDX: 0000000000000000 RSI: ffffffff8afc6f60 RDI: ffff8880b8f3cf20
RBP: 0000000000000001 R08: dffffc0000000000 R09: 1ffffffff21b28a0
R10: dffffc0000000000 R11: fffffbfff21b28a1 R12: dffffc0000000000
R13: 00000000000001a0 R14: dffffc0000000000 R15: 0000000000000002
 rcu_read_lock_held_common kernel/rcu/update.c:112 [inline]
 rcu_read_lock_held+0x1e/0x40 kernel/rcu/update.c:348
 lookup_page_ext mm/page_ext.c:240 [inline]
 page_ext_get+0x193/0x2b0 mm/page_ext.c:509
 page_table_check_set+0x51/0x6f0 mm/page_table_check.c:114
 page_table_check_ptes_set include/linux/page_table_check.h:74 [inline]
 set_ptes include/linux/pgtable.h:238 [inline]
 copy_present_pte mm/memory.c:979 [inline]
 copy_pte_range mm/memory.c:1083 [inline]
 copy_pmd_range mm/memory.c:1168 [inline]
 copy_pud_range mm/memory.c:1205 [inline]
 copy_p4d_range mm/memory.c:1229 [inline]
 copy_page_range+0x248d/0x3600 mm/memory.c:1323
 dup_mmap kernel/fork.c:764 [inline]
 dup_mm kernel/fork.c:1692 [inline]
 copy_mm+0x11a8/0x1ca0 kernel/fork.c:1741
 copy_process+0x16d3/0x3d70 kernel/fork.c:2506
 kernel_clone+0x21b/0x840 kernel/fork.c:2914
 __do_sys_clone kernel/fork.c:3057 [inline]
 __se_sys_clone kernel/fork.c:3041 [inline]
 __x64_sys_clone+0x18c/0x1e0 kernel/fork.c:3041
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f84e4185e93
Code: 1f 84 00 00 00 00 00 64 48 8b 04 25 10 00 00 00 45 31 c0 31 d2 31 f6 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 89 c2 85 c0 75 2c 64 48 8b 04 25 10 00 00
RSP: 002b:00007fff07cc6808 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f84e4185e93
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001
R10: 00005555915aa7d0 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000036 R14: 0000000000044d53 R15: 00007fff07cc69a0
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/31 06:17 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_clone
2025/12/12 09:20 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_clone
2025/12/09 09:12 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_clone
* Struck through repros no longer work on HEAD.